Seperate phono better than pre?

Are most stand alone phono stages better than ones intergrated into a preamp. I really like my Sonic Frontiers SFP-1sig. but am leaning towards and upgrade possibly in the direction of a Rhea or the full Janus preamp. Would either be an upgrade or would my stand alone be better than the phono in the Aesthetix Janus?
Opinions are greatly appreciated.

I should add that the Ayre phono is on my list as is the newer Sonic Frontiers phono1
your phono amp is very nice(a classic)....however....the synergy/compatibility of a built-in in a quality pre is generally the way to go.
Don't assume it is better just because it is in a separate box. I owned a CJ preamp with phono a while back that was 73% more expensive than the same model without the phono. Or put another way the phono was 43% of the price of that preamp. It was a steal for the price. Having it in the chasis kept the price down, even though the price was what you might call high.
I have owned both the Sonic Frontiers you mention and the CJ pre with phono that Sugarbrie mentions. The Sonic Frontiers was an improvement over the CJ but my current Plinius is better than either. The short answer, I think, is there is never a "best" and no absolute statement that separates are better than good integrateds but there are many more very good phono pre amps as separates than integrateds to choose from. Happy hunting and from what I hear the Aestetix would be an excellent choise.
Considering the cost for a very good interconnect and the need for another power cable if going separates, I suspect the Janus is quite a steal of a deal compared to buying the Calypso and Rhea.