After playing with 4th edition with some time, though only as the occasional standalone adventure, my players and I have decided to drop back to 3.5 for a campaign because it will be a semi-sequel to our last major storyline, which was set in 3.5 Eberron.
God, how I missed the 3rd edition character creation process. I know that a lot of it is just nostalgia and familiarity, but I have so much fun with it. And no, it's not a fair comparison because of the number of splatbooks available for 3rd and the extreme lack of balance in certain classes/spells/feats, but it just feels like you can make far, far more customized and interesting characters in 3rd edition.
Even though I'm going to be DMing, we're a small group so I'm making a PC...so I'm really having a blast. My guy is a super-simplified wizard, both to keep myself from stealing the show and to keep him manageable while I'm also trying to run the bad guys. I wanted him to be as effective as possible in propping up the party's fire-power, while not really being able to bypass obstacles through magic.
So, 10/10 points for awesome 3.5 character creation.
But minus several million points when I started to look at the monster manual stat blocks again. I nearly had a seizure. Dear god, I forgot how nightmarish it was to try to put together a decent combat encounter in 3rd edition. Luckily, I'll be using a published adventure...but even then there's a LOT more text to keep track of than in 4th edition.
3rd Edition: Delicious for players, hell for DMs.
4th Edition: Bland for players, heaven for DMs.
Really, the biggest thing that 3rd edition needs is a re-think of monster/NPC stat blocks. One of the biggest changes from 2nd to 3rd edition is that monsters were treated as characters, with stats and skills and feats and all that. It's one of those things that Seemed Like a Good Idea at the Time. The problem, of course, is that monsters don't need that level of detail. That's something that 4th edition gets right. Monsters/NPCs there are trimmed down to only what you need to do, and they are based on guidelines that are very easy to use if you want to make your own custom enemies.
The interesting thing, though, is that there's no reason that you can't do the same thing for 3rd. If you're willing to put in a little work, it would be easy to come up with similar stat/level guidelines and a simpler type of monster stat block. Going forward, that's exactly how I'm going to operate. My enemies will NOT follow the rules for players.
For example, at the end of our last campaign I assembled what I really believed was a truly epic final boss fight. It was a Mind Flayer with a ton of Psion levels, who started the combat with a stack of about 10 defensive buffs to ensure that he wouldn't be disabled/killed in a round. Building him took over a day. The end result was fantastic, but I'm not sure if the effort is ever one I'd look to duplicate. And damn, then there was the amount of bookkeeping required in battle. Recalculating stats as buffs get dispelled, keeping track of power points, using magic item charges, etc...
If I were to do that today, I'd definitely follow the 4th Edition process. I'd aim for a AC/saves/SR that would work __% of the time, and not care how I got there. I would pick a good psionic power and just give it to him at-will. I'd pick a REALLY good psionic power and make it an encounter or recharge power. I would give him a 4th-edition-style "action point" and/or something he can use as a swift action. I would allow Dispel Magic to apply a stacking debuff to his defenses (-1 to everything?), to simulate stripping away of defensive buffs.
I'd also give him a 50% chance to shrug off any condition, once per round just like 4th-edition saves. (I can use the same mechanics for the players to shrug off some of the monster's abilities.)
This basically eliminates the "save or die" problem and gives me a system should enable me to control how long I want the monster to survive (figure PC's average damage X hit chance, multiply out by how many rounds I want him to live on average.) By having a more durable monster, I can also make his damage more reliable, but generally lower and less "bursty". He'll be a threat, but a less random one. Plus, if it's a longer fight then it increases the importance of tactics, positioning, and cooperation.
Right away I have a monster that I can build in minutes, not hours, and that is very easy to manage in combat, leaving me with plenty of time to coach players or add flavour text.