Ok, here's my synopsis of the Ruby/Emerald debate. I've faced them, and beat them, without cheats. Here's my analysis of all 4 Weapons:

Well, I pulled FFVII out of my closet (literally) and began replaying the timeless classic. After 40 hours of gameplay, I finally made it to disc 3 (I did A LOT of training). Thus began my hunt for the Weapons. If you don't know what the Weapons are, here are a list from weakest to strongest, and my synopsis of the battles commencing:

Ultimate Weapon: Encountered about 3/4 of the way through disc 2, and anytime during disc 3. For a Boss to have such a powerful name, I beat it no problem, using Bahamut ZERO + Quadra Magic. The first 3 times I faced it (Yes, you face it a total of 4 times), I used this little trick to beat it right off the bat. It only has 10,000 HP in all 3 battles before it runs away. The 4th time I faced it, it took a little more coaxing in order to thwart this giant, as it had 100,000 HP. Thanks to my Command Materia, Enemy Skill, I was able to learn the ability, Shadow Flare. Shadow Flare is the Final Attack Ultimate Weapon uses before it dies, taking a chunk of health from one person. Thus, I acquired the Ultima Weapon.

Diamond Weapon: Ok, this one was a little easier, yet longer. You encounter this creature right before you invade Midgar at the end of disc 2. With a meager 30,000 HP, it's not that hard to beat. Unless you're counting the fact that all physical damage you do to it is pretty much useless. I disposed of this creature in a matter of minutes, as I kept bombarding it with Bolt 3, Fire 3, Ice 3, and random summons, including Bahamut ZERO.

Ruby Weapon: Okay, this was an insane battle. First, I'll give you its stats:

Ruby Weapon
LVL: 59
HP: 800,000
MP: 2,560
Immune to: Gravity; Water
Drains: Fire
EXP Gain: 45,000
AP Gain: 50,000
Gil Gain: 30,000
Item Gain: Desert Rose (Used to acquire Golden Chocobo)

Attacks (From what I've seen):

Ruby Ray: Deals 7000-8000 points of damage.
Whirlsand: Disables and removes 1 character in your party. Usually used twice.
MP Tentacle: Drains MP by ? points.
HP Tentacle: Inflicts damage to HP by about 2000 points.
Ultima: Used as a counter attack.

The first and foremost thing I did was obtain the Knights of the Round Table materia. It took about 5 hours to get the Golden Chocobo, but it was well worth the wait. This is my party stats:

Cloud:
LVL: 88
HP: 9,999
MP: 999
Immune to: All status effects (Besides Haste, Slow, Stop)
Weapon: Ultima
Materia (From what I remember):
HP Plus + MP Plus = Speed Plus + Speed Plus = Double Cut + Mime = Bahamut ZERO + Quadra Magic
Armor: Wizard Bracelet
Materia: Knights of the Round Table + HP Absorb = Final Attack + Revive = HP Plus + Speed Plus = W-Summon + Long Range
Accessory: Ribbon

Tifa:
Disabled from Whirlsand

Vincent:
Disabled from Whirlsand

Ok, it took me about 4 tries in order to beat it. Let's just say I ended up winning using Knights of the Round Table once, failing to use it the second time due to not having it leveled up, and then miming 4 more times. Thanks to HP Absorb, it's Ruby Ray wasn't able to beat me. Thanks to Desert Rose, I was able to acquire my second Gold Chocobo.

Emerald Weapon: Took me a total of eight tries to beat this guy. Finally, I got lucky.

Emerald Weapon:
LVL: 99
HP: 1,000,000
MP: 100
Immune to: Earth
Drain: Ice; Water
Weak: Lightning
Strong: Gravity
EXP Gain: 50,000
AP Gain: 50,000
Gil Gain: 50,000
Item Gain: Earth Harp (Used to get the 3 Master Materia)

Attacks:

Aire Tam Storm: Deals damage equal to number of materia X 1111 to all characters. In other words, if Cloud had 4 Materia orbs on him, he would take 4444 points of damage. If you read "Aire Tam" backwards, it says: maT eriA, or Materia. Go figure.
Emerald Shoot: Deals massive damage to one Character. About 7000 damage.
Emerald Blast?: Deals damage equal to 65% of current health.
Blue Eye: Deals about 2000-3000 damage average.
Yellow Eye: Deals about 500 Mp damage.
Revenge Stamp: Deals about 1500-2500 counter damage.
Stomp: About 2000 damage on average.

Here was my party:

Cloud:
LVL: 91
HP: 9,999
MP: 970
Immune to: All status effects (Except Haste, Slow, and Stop)
Weapon: Ultima
Materia: Long Range + W-Summon
Armor: Wizard Bracelet
Materia: Mime + Double Cut = Final Attack + Pheonix = Knights of the Round Table + HP Absorb
Accessory: Ribbon

Tifa:
LVL: 89
HP: 9,999
MP: 999
Immune to: All status effects (Except Haste, Slow, and Stop)
Weapon: Crystal Glove
Materia: Long Range = Time + All
Armor: Mystile
Materia: HP Plus + MP Plus = Bahamut
Accessory: Ribbon

Vincent:
LVL: 89
HP: 9,999
MP: 999
Status: Hasted
Weapon: Death Penalty
Materia: HP Plus
Armor: Escort Guard
Materia: Contain + HP Absorb = Barrier + All
Accessory: Sprint Shoes

Ok, basically, I started out with Omnislash. Thanks to Ruby, I left with my Limit Bar full. Then, I went all out with Knights of the Round Table and Mime for a total of 6 hits until Emerald killed me, in which case Phoenix brought me back to life. From there on, I continued to used 4x Cut and all 3 of my final Limit Breaks: Omnislash; Final Heaven; Chaos. Whenever Emerald decided to use Aire Tam Storm on me, Phoenix would just bring me back. Well, as you may know, it is safe to have the Underwater Materia. Well, I didn't. So, I had to beat it in the allotted 20 minutes. It was tough. Like I said, it took me 8 tries to kill it. I was finally able to kill it with 4x Cut, doing the last 36,000+ points of damage. Luckily, I had exactly 1 minute to spare.

Here's an analysis of my damage record:

Omnislash: 5600 points X 15 = 84,000
Knights of the Round Table = 8200 points X 13 X 2 X 3 = 639,600
Tifa's Limit Once: I'd say it was about 10,000 points of damage, as Emerald's eyes were out.
Vincent's Limit: I'd say he did a total of 40,000 points of damage before he was disabled.
4x Cut: 9999 X 4 X 6 = 239976
Phoenix: 4000 X 3 = 12,000
Aire Tam Storm: -21,000 (It healed him by 7000 points each time)
Total: 1,004,576

Those are estimated, so it may be off. But, as you can see, I cut it very close. I had one last Final Attack with Phoenix before I ran out, and I only had 1 minute before I had to restart. Talk about cutting it close.

So, I see it as:

Ruby: Has less HP, but have to fight alone.
Emerald: Has more HP, more attacks, and takes more time preparing.

I'd say Emerald was harder.

Off topic, I'm now the proud owner of:

3 Gold Chocobos (I bred my first chocobo with my second using another Zeio Nut)
1 Master Summon Materia
1 Master Command Materia
1 Master Magic Materia

Now all I have to do is go to the Northern Cave and beat the final boss.

BTW, I've been playing this game for 66 hours without any cheats.

Heh they're both easy. All you do is link HP Absorb with KOTR. And have somebody Mime it. Easy strategy. But back to the question. I feel its Ruby. He always used to whip the crap out of me before I used the strategy I stated. Emerald I could last awhile against him but he'd eventually get me.

lol i was so close to beating emerald so ruby i think is more difficult cause i feel ive never really laid a sratch on it!!!!

Mod Edit: Please put more effort into your post.

i really cant add more as all the stats are put up already! i havent defeated either of them! i answered the question what more do u want exactly???? i am sorry if i 'offended' anyone from my short post last time lol...jeez io better carry on before i get told off again..... nah
Ruby more difficult than emerald in my opinion what more need i say???

I personaly always found Ruby harder than Emerald, just because I dislike his ability to get behind you.

Hey Horus00 you rally did your homework didn't you? Well In my experience, I must say, that I think Emerald was toughest. I mean, if it wasnt for my underwater materia...yeah. Well I am going to try the slots trick with cait sith. I hope it works.

ruby is heaps harder the first and the 2 and the 3 andalso the 10 timei went up against him i never got a single hit in the pig (but he looks cooler)

emerald i killed him when i was about all around the level 60 mark i dont remember how but i used KOTR and mime but thats it