I have an unhealthy love for FE7. FE8 is fine, but flawed.
FE7: +Great unit balance +Great map design with many primary / secondary objectives +Lots of chapters and nice difficulty variety +Great cast and an interesting story premise -Some don't like the linearity
FE8: +Branching classes +Great music +Post-game content -Weak, hackneyed story -Bland cast of characters -Very, very easy
7 is great, that's about all I can really say, since it's better if you actually play it.
8 is just a dumbed down version of Awakening. Each class has 2 options, a few have skills on them (Generals are ridiculously overpowered by the way). There's an RNG trick in this one so you can actually get "perfect" level ups every time, but you'll need to reach a certain chapter first. --- You get the option to skip the tutorial stuff, so you'll start right at the balls. - Jabodie