Might and Magic. No doubt. Most real content and best balance and you can actually feel that they were made to for playing and not for marketing.
The first wizardry games are just dungeon crawlers where mainly your patience to farm enough XP before going to the next level is tested.
Part 6 and 7 had an interesting spell system and more than a dungeon to discover, but the main skill tested are luck manipulation by rerolling or reloading (they're badly balanced), XP farming and patience to waste your time. It increases the total game playing time but doesn't make a game better if you have to watch your party resting for 30 minutes real time to get their mana back or do other repetitive stuff or if riddles are so illogical that you need a fortune teller to solve them. Many things like the so called different W7 endings are just marketing fake (instead of letting you reload when you're screwed it's called "ending" and saved, there's only one real disappointing ending with disappointing end sequence ("you haven't really finished, buy W8").
Hardly any content remains when you remove the artificial lengthening, it's a myth that those games are big, they're just slow.
Wiz6+7 were considered difficult because they required luck manipulation by reloading, MM3 was considered difficult because it required using your brain.
Part 8 might be the best Wizardry game, but it has slow combat and level scaling.
The Ultimas I tried are just too painful to play, maybe the later rpgs are nice if you want to play "The Sims" and your computer isn't fast enough. Being able to bake bread and having to talk about the weather with many NPCs might be essential for marketing, but not for the game playing fun. The supposedly best U4 has a educator attitude which disqualifies it as rpg. You may not choose your class, WE judge what class you have to play, it's not about playing your role, it's about playing how WE want you to, WE judge if you play correctly and don't let you proceed if you don't, your parents told us to do so. That seems to be the attitude behind the later Ultima games too. Avatar, make your mummy proud by behaving well.
The Might and Magic games (at least part 1-7 which I played) on the other hand show that they were made to please the player and not only to make money. Compared to the other series they're extremely fair and balanced and offer more real content instead of time wasters.
The first part had bad graphics for it's time, but the gameplay was fine. Instead of a simple dungeon crawl it offered a world to explore and I loved the ending.
MM2 has nice graphics and a very big world.
MM3-5 made a great step forward. Intuitive to play but hard to master. Great automap and huge worlds to explore. Gameplay was optimized so you'd be able to explore big areas fast. Fully turn based so you can take your time thinking, but still feels real.
MM6 had a great skill and spell system. You could choose between the still great turn based combat or real time action. Although it's fast paced it takes a long time to complete because the world is extremely huge.
MM7 optimized the skill and spell system even further. Its shorter than MM6 but stil a big game.
While I wouldn't dare to torture anyone today with classic Wizardry or Ultima games, the MM games are still fun to play today.
