Favourite aspects include:
- how well the theme is tied to the mechanics (complain all you want about the number of conditions, etc, but no other game makes as much thematic sense to me as MW in terms of what a condition ability does in game mechanics vs what it's supposed to represent)
- no luck-of-the-draw (e.g. spell books replace shuffled decks)
- no uncertain resource system (e.g. no "lands"; predictability of resources; can save mana or spend mana, but aside from some small unknowns like Mana Siphon getting dropped on you, or Essence Drain, or whatever, you can usually predict with reasonable certainty whether or not you can cast your spell this turn/next turn or by turn 7/8/9)
- Dice. In general, I'd much rather have uncertainty come up in the power of an attack or whether an effect triggers or a defense works than on luck-of-the-draw in when I get mana or a powerful threat or a needed counter to an opposing threat.
- Balance, including skill to luck ratio. A good experienced player will generally win against a weaker inexperienced player, but there is some chance that an upset can occur. Also, there are good and bad match-ups between mages, but player skill and outguessing your opponent at a key moment, or even a good/bad dice roll, can still flip the balance, and allow you to pull out a win in a bad match-up.
- The game outside the game. I enjoy building books, just like I enjoyed building MtG decks. The difference is that a MW book is much more likely to play the way I expect than the luck-of-the-draw of a MtG deck, which might work as intended 1/4 of the time (at best).