I don't think there is a definitive answer all joking aside , I find both have +ve / -ve aspects.
I like the bed on the Rubi 700/1200 because the
tile doesn't slide around to very much which helps when lining up 2 marks on a large
tile.
On my little Sigma I like the base as if I'm doing some
standard mosaic , it sits over the centre bar nicely if I want to cut a complete row. I also like it because its so small and is usable in a tight space with ease( although generally I like to set up in a diffo room from wherer I'm tiling )
I don't like the metal bases on sigmas as I find that on an older machine the bed can move around a little.
I dont like the bigger sigmas as I feel they are just too chunky and awkward to move around and have vision of it banging into something. My Rubi comes out of case and sits on thast case and just feels more streamline. Again this is only personal opinion.
I dont like the breaker on the TS as I don't really think they're any good for todays stuff , just the odd kitchen / cheapo bathroom
tile now.
Diggy