Well, I like them all. However, these are the major plus points for me:
- Really aesthetically-appealing graphics, such as slopes, etc.
- Cutscenes like Fr/Lg
- Good music, particularly Kanto (Viridian Forest and Saffron City, anyone?)
- Pokemon following.
- Safari Zone! God, if they'd made others anywhere near as good, I might've used them....especially brilliant when compared with Pastoria's Great Marsh in Sinnoh.
- The Pokedex. Easy to navigate, contains all Gen I and II pokemon, and a 5 evolutions....I just like it.
- The pokemon. Generally, whilst I like some later generations pokemon, despite starting from Gen III I prefer Gen I/II pokemon (probably because I got the pokemon annual 2000, which had the first 251 pokemon in it, and got really excited every time I saw one of those in my games).
- The random order you can do gyms 5-7!
However, Lyra really irritates me, I do wish I could delete contacts (I don't want anybody who isn't either really strong, or going to give me evolutionary stones), and the focus seems to be on Kanto pokemon. Falkner could've had Hoothoot and Noctowl, Bugsy could've used Heracross, etc.etc. although Chuck having a Poliwrath and Primeape pleased me simply because I like how challenging Poliwrath is.