Also, whether its also a series you are trying to complete a collection of, is there a series you are attempting to play through either all in a row or over time.
For collection, I'm working on getting as many of the Final Fantasy titles as I can. I really haven't decided that if at this point I'd like to actually go for a collection of all of the titles, across all consoles, or if I want to just get the copies I'd most likely play, so ps1, ps2, and the various mobile copies as well. I'd also love to get a hold of the FFVII titles on PSP and where ever else those are available.
I would love to eventually play through all of the FF titles, as of now I've only finished FFX, and have only played XIII and VIII beyond that, but right now I'm still working on late game FFX so I'm not sure when I want to start one of the older titles.
In terms of collections I may finish sooner rather than later, I'd like to get the rest of the Crash Bandicoot titles for ps1, games I grew up on and would love to own and play through again.
Zelda is another big one for me, only having played a bit of A Link to the Past and Ocarina of Time in the past, its a huge area in gaming that I've missed out on.
Finally the Metal Gear series. I've played and completed 4 and played a fair bit of 5, but I've never finished the older titles.
I feel like the second half to this post is more, what are some bucket list games you need to play haha at least for me.
Some other series I'd be interested in though I know very little about are the .Hack games, Xenosaga, and potentially the Tales of games. I've never played any of these games though I do own the first Xenosaga, but have always been interested in them.