Unless you really need that pea green LCD retro feel I'd go with some form of either the GB Pocket or import the GB Light (which is a pocket basically but uses an indiglo screen that lights up in the dark.) The Pocket used 2 AAAs and the GB Light has 2 AAs. Batteries aren't cheap if you slam through them, but if you get an energizer kit with 4 batteries and a charger for maybe $20~ you'll be set. I did that back in the GBC/A (pre SP) era and it did wonders and lasted the life of the need of them and then some. If you figure you'll end up buying a big of box of batteries about the same cost that are one shot use it makes sense.
If you can take it, just because it opens up a few more games and is still 90s retro I'd get a GBC. If the lack of a light there bugs you, there's a stupid easy way to fix that cheap. You can get a Kitsch Bent LCD for $12 and add that right in with 2 solder points, or you can find a broken SP 001 system, harvest the light panel from it, and slide that into the GBC frame and it works nicely too. Both are obviously optional if you have a good light source or are outside enough it won't really be necessary.
If you can take it, just because it opens up a few more games and is still 90s retro I'd get a GBC. If the lack of a light there bugs you, there's a stupid easy way to fix that cheap. You can get a Kitsch Bent LCD for $12 and add that right in with 2 solder points, or you can find a broken SP 001 system, harvest the light panel from it, and slide that into the GBC frame and it works nicely too. Both are obviously optional if you have a good light source or are outside enough it won't really be necessary.