I'd probably pick Metroid for convenience since the best Metroid games are quite scattered as far as systems. the Donkey Kong idea is nice but a bit too ridiculous imo, Nintendo would never put together like 15 Donkey Kong games. for the older Metroid games (Wii and prior) I could see it being possible

I would say Fire Emblem or the Famicom Wars franchises would be the best options.

Both have a number of older releases that were never released outside of Japan and classic entries that were which a number of old fans and new might want to sample preferably in a remastered package.

Metroid Prime Trilogy HD

Mario Party 1-3, combine the boards and minigames into one big game, using the mechanics of 2/3.

Pokemon (Rainbow?) Gens 1-5 with an entertwined story, so you can visit each area some way from 1-5.

Metroid, Super Metroid, Fusion and Zero Mission.

I doubt I'd buy any of those. I voted for Metroid though, as there's at least a chance that I'd consider it, assuming it included Super Metroid. There could also be a compilation of Mario platformers that I'd consider, depending on the games included.

I tried to play the Metroid Prime trilogy last year.  I just can't deal with the crappy cameras from the the first game.  I have the problem with many games from PS1 era through the beginning of the last generation, when they finally started getting cameras and controls to not suck.  

We have Samus Returns so it's not required.

Super Mario 3D All-Stars.

64, Sunshine, Galaxy 1 & 2, and 3D Land remade with Odyssey's lighting, textures, and graphics. It can also fix the issues with 64 that have dated (camera and control) and also fix the main problems I had with Sunshine (Blue coins, blue coins, BLUE COINS!)