Yeah. The robot mod is cool too. Legends is Japanese series for combiner war? Titanium is platinum edition you mean?
The best are those 3p Legend scale ones. Perhaps the MP scale Ultra Magnus made by XTB will be the best of all of them.
I presume that the OP is referring to figures that are versions of the G1 character. Out of the two that I have, I'd probably say Siege edges out CW for being truer to the spirit of the G1 character, as a white Optimus Prime lookalike in a suit of armor in robot mode. CW's alt. mode, however, is closer to and more utilitarian like the G1 version, in that it can actually carry more than two cars bigger than Micromasters. Still, Siege is probably my favorite of the two.
Siege followed by G1. I do have a soft spot for the RID figure. One of the first non G1 Transformers I bought. The greatest flaw of any Ultra Magnus toy is not being repainted as Delta Magnus.
Concept wise, the Legends/CW leader with the PE upgrade set (giving him a core robot). Execution...is another matter, due to the visible hollow parts, incomplete armor around the arms, the plastic being too thin on some parts, and the just hollow feeling. Siege corrects all this, but he's very small for a leader and I don't like the parts forming. I like the Animated one, but the pelvic thrust is a bit much and I don't care for the animated style. RiD 01 is both impressive (sold parts, weight thanks to good thick plastic and a functional car carrier), but at the same time he does have very very very very long legs and very little upper body...and ball joint that won't hold up his (lower) arms. Titanium is a nice idea and the first all-in-one Magnus. But you can see that it wasn't designed by the TF department of Hasbro, and there's too much die cast. G1 is nice, but a brick. I'm still waiting on the best/perfect Magnus (and I already sold the MP a long time ago).
Combiner Wars Ultra Magnus. The IDW design and inclusion of Minimus Ambus makes the figure perfect. Hands down my favorite figure of all time. Siege Ultra Magnus is good as well.
Same here. Siege is the perfect G1 update. I like the size, and the parts-forming doesn't bother me due to that being how the G1 version did it. Animated is an awesome mold and quite perfect for the character. -The RID version is quite nice in alt mode, but that bot mode isn't something I enjoy. -Always wanted the Titanium one. Looks perfect for a Legends (scale) display. -CW version is... not for me. Actually, I dislike nearly everything about it.
The Combiner Wars Ultra Magnus with the Perfect Effect PC-17 Core Magnus and the X2Toys XT009 upgrade kit. It is my definitive Ultra Magnus.