To be honest I would play the first one and forget the rest. There dumbed down and rather rubbish compared to the first one.
I feel that for example streamlining the clumsy inventory management is just for the benefit of the later parts of the game. For me ME1-3 are about everything else than the shooting and fighting and these "deep" inventories and swapping of ammunitions and extra bits and pieces of weapons and min-maxing of character development just get in the way of experiencing the world, atmosphere and story. Those choices add very little to the experience and mostly distract from the things that matter.
And normally I'm one of those people who uses excel to solve optimal sets of gear & skills for games...
Biggest problem with the series I see is that you are often given the chance be a psycho-sadist or fairy goodmother. There is no option of being selfish without being absolutely evil being enjoying torture. Where is my chaotic good?
Most of the time npc-characters are such that i don't care too much. Or maybe i do, but my priorities are clear -> i need their medi-gel of which they'd better hand me voluntarely 80% after i've saved their asses. Instead the options are "nuke the village and loot everything" or "ask nothing but some hugs and kisses in return of saving them". Thid unfortunately takes away the moral choice, making it a choice between good and evil instead of choice between different good or different evil.
Well, this is a bit extreme view, as it does have some bit more "moral choices", but it is still very clearly b-class writing instead of the normal c-class or non-existent storytelling in computer games. And this should be read as a praise. Games with better writing are genersllu very few and far in between.
For anyone who wants pixel perfect, precise and good shooting feel don't necessarily need to bother. But for those that like to have decent reasons for shooting might want to look more carefully towards Mass Effect.