Loved the game, played every route. My recommendation is to play the game with whatever heroine you want (I did Lesteena for instance first and foremost).
There are a few heroines that you can only do after NG+ but otherwise if the battles are an issue for you, you can just use a trainer to get through the "gameplay" aspect of it.
Most of the game is pretty linear with maybe 2ish hours worth of content related to heroines in specific, otherwise many share similar "routes" and only minor changes come from choosing them.
The recommended route is mainly just due to related plots diverging from the main heroine.
Aselia->Esperia->Orpha->Uruka->Lesteena->Kyouko->Tokimi.
Aselia is the main heroine and relates to Esperia, Orpha, Uruka, the later three slightly diverge and maybe Orpha only having a bit more additional content related to her specific plot.
Lesteena is pretty separate from the above 4 so there isn't really a lose in playing hers (and after playing all the routes I personally still enjoyed hers the most but that's personal opinion).
Kyouko and Tokimi are NG+, the later was a good route and probably my second favourite next to lesteena.
Then there is of course the failed-to-get-heroines route and the bad route...
tl;dr choose whichever YOU personally like, you won't miss much, then if you want to go back and do the rest and if you dislike/annoyed by the gameplay, trainer it.
Don't care what anyone says Eien no Aselia is one of my favs.