I get the PS3 version of Zesteria once it gets a bit cheaper.

Tales of Meh, my opinion of the series after Symphonia.

Played both Symphonias and dabbled in Phantasia on emu

You need to play Tales Of Destiny. Great game.

Which ones have you played, because Symphonia is objectively one of the weakest in the series. Worst 3D Tales battle system by far, and while story is subjective, it wasn't good.

People seems to think that Sales figure is only reason why Tales series are not coming into Nintendo console...

Tales never really left PlayStation. The series has had an off and on relationship with Nintendo, and none of the Nintendo released titles have remained exclusive to Nintendo systems.

Tales of Phantasia: SNES originally, ported to multiple systems since
Tales of Destiny: PS1/PS2
Tales of Eternia: PS1/PSP
Tales of Destiny 2: PS2/PSP
Tales of Symphonia: GCN originally, ported to PS2, later received an HD remaster for PS3, coming to PC
Tales of Rebirth: PS2/PSP
Tales of Legendia: PS2
Tales of the Abyss: PS2 originally, ported to 3DS
Tales of Innocence: DS first (JP only), enhanced port for Vita (JP only)
Tales of Vesperia: 360 first, PS3 later (JP only)
Tales of Hearts: DS first (JP only), completely remade for Vita
Tales of Graces: Wii first (JP only), PS3 later
Tales of Xillia: PS3
Tales of Xillia 2: PS3
Tales of Zestiria: PS3, PS4, and Windows
Tales of Berseria: PS3, PS4

Count:
Playstation - 10 Tales games received first, exclusively, or as a console exclusive, up to 16 including enhanced ports and the one remake
Nintendo - 4 Tales games received first, up to 5 including the Abyss 3DS port
Microsoft - For the funsies, they got one first, and in a somewhat rare case, it was one where we did not get the enhanced edition in the west

There are also a ton of spinoffs largely focused on Playstation systems.

Tales of Vs: PSP (JP only)
Tales of the Heroes: Twin Brave: PSP (JP only)
Tales of Symphonia: Dawn of the New World: Wii first, PS3 later
Tales of Phantasia: Narikiri Dungeon: GBC first, remade for PSP later (both versions JP only)
Tales of the World: Radiant Mythology: PSP
Tales of the Tempest: DS (JP only, game widely considered to be complete crap, known courtesy of an available fan translation)

As much as people seem to think Tales has had a presence on Nintendo, the main games have been largely absent, or moved to a Sony system later. In the end, Sony is the home of Tales. The series may periodically make an appearance elsewhere, and it is gaining a PC presence slowly at this point, but on the console front, Bandai Namco seems pretty content sticking to the PlayStation.

Why? I've played Symphonia (though have not beaten it) and I found it weaker than Vesperia, Graces and Xillia, which are the best tales in my opinion.

i like tales of zesteria, xillia and vesperia.

Symphonia sold the best in the US, but Xilia has best sales WW for the series.