The Ganbare Goemon series. Every game that's ever made it to the west has been phenomenal. The two N64 games are some of my most treasured memories of that console. The last true game in the series came out in 2005 on the DS, which I heard was pretty good though it was very Japanese heavy and difficult for a non-speaker to play. He's basically only been used as a pachinko machine mascot ever since, though even the last time he was seen in that context was 2011. He did get included as a Bomberman Switch costume in a very recent update, however.
Unfortunately he's a Konami property, and it's very likely we'll never see another Goemon game again. Which is a damn shame, because his games are a goofy-ass, robot-punchin', coin-collectin' good time.
Kya: Dark Lineage. It's only one game so not a series, but the ending totally says "continued in part 2" or something and we never got it, and now I think Eden Games is gone?

First one that came to mind for some reason, not counting games with only one entry that may be better off not being re-touched.
Tobal might be a nice idea too; imagine the gameplay of the original game with ArcSys's Dragon Ball FighterZ style.
Ty the Tasmanien Tiger need to come back
Didn't even know he had a third game before 2015 for it NEVER come to europe
This. Out of all of MK clones and inspired games, this to me was the most interesting. Modern graphics and game mechanics would make this incredible. Hell, let the same team(s) who did the new Killer Instinct do this.
Ecco the Dolphin
At the end of Ecco: The Tides of Time,Ecco is instructed to destroy the Atlantean time machine by the progenitor of all life on Earth, the massive sentient double-helix Asterite, so he heads to their sunken city to execute the task. The Vortex Queen - a defeated alien from another world - beats Ecco to the time machine and travels back in time, integrating with life on Earth and giving rise to arthropods. When Ecco arrives at the machine, he decides not to destroy it, but to again use it, departing to a time unknown...
Ed Annunziata, Ecco's creator, was once asked on Twitter what his plans were for an Ecco 3. He wrote:
Ecco 2 was released in 1994, and it's been 23 years since its release (the Dreamcast spinoff was cool, but its own continuity). The gameplay was incredible, dolphins are fun to play as. Eating fish for health, managing on oxygen meter, blasting alien heads off with your sonar - the gameplay was really solid. Maybe introduce Metroidvania elements? Let's bring back Ecco. Ed Annunziata's down for it. Call him up, Sega.
I would say so (it's been 12 years since Resurrection and 17 since ME2), and also wholeheartedly agree.
Grandia & Skies definitely. CC not sure if that counts considering it's a sequel to the most popular RPG not named final fantasy but it is lesser known
Non-Obscure returns I want: River City Ransom, Mystical Ninja Goemon, Front Mission, Jet Set Radio
River City has had 3 (non sports related, as there's one on Steam, and on PS3) games by the JP IP holders come out in the last 2 years. River City Tokyo Rumble, River City Knights of Justice, River City Rival Showdown, and there's also the "indie" NA released sequel, River City Ransom Rival Underground, which came out this year. At least 3 out of the 4 are pretty solid. (not a fan of the Knights of Justice style)
Hopefully, a large collection of the games (that is out in JP on 3DS and slated for Switch) will be releasing in the US next year.