Suikoden V has good music, many characters, and an awesome political story. There are many twists and turns along the story but not as many as XG/XS. SV is far better than SIV but still not as good as SI and SII.
Tales of the Abyss is a very long RPG, has a good storyline but not comparable to XG/XS's.
Dark Cloud 2 differs from Dark Cloud 1 in graphic style, but is the same thing in gameplay. If you are going to play DC, play DC1 first, it has better music and town building gameplay.
Overall, all the ones you listed are good choices, but none of the above three offers the kind of deep storyline, music, nostalgia, sci-fi atmosphere, plot and epicness that the Xeno series offers. The Xeno series has a "it" factor that is more akin of an experience than just playing a RPG.
How are Xenogears and Xenosaga related?
After you finish XG, at the end it shows "Epsode 5", there are also references to XG found in XS, but that's about it, the two are not related. But they both have giant mechs and other sci-fi elements. Most fans that like XG will also like XS and versus vice.
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KOS-MOS: There is no connection between my current systems and your life functions.