The "big money" combo requires separate priest and cipher, because a cipher cannot cast Ancestor's Memory (for the Brilliant buff) on themselves, and that is the buff that potentially allows unlimited casts of Salvation of Time (and thus indefinite durations for any other buffs).
Ascendant works well either solo or multiclass, but you should think of it more as a tradeoff, where you sacrifice -1 PL to get significantly increased focus generation. Ascending for the +3 PL bonus can take quite a while to assemble the focus at the start of the fight, which is generally the part of the fight that you most want to be spending your time casting actual spells (like, say, Ancestor's Memory on your Priest so you can get the sweet, sweet SoT spam going). Once you get things under control, you can either Ascend (and stay there forever with SoT spam), or don't bother because there aren't all that many fights where you aren't already well on your way to mopping up before you finish ascending. That's true for single-classed, anyway, if you multiclass rogue or ranger, you will gain focus a lot faster and it becomes a little more feasible to Ascend soon enough to really make a difference. Because action speed is so worthless in turn based, Time Parasite is not the sexy thing it is in real time, so the only real draw in my mind for a SC cipher is Driving Echoes, which basically makes penetration as a mechanic a nonissue. However, if you are paying attention to gearing and spell choices, penetration isn't as big a deal as all that.
Beguiler is interesting as well, because you can basically spam Deception spells to gain focus instead of weapon attacks, at least early in the fight when there are many enemy targets. Once the board clears, they instead gain focus SLOWER because they get a lower total multiplier on their damage. But they are more friendly with caster multiclassing, spending the first couple of rounds maxing out their focus (and throwing around AoE debuffs while they're at it), and then rationing out their focus for the rest of the fight along with spell casts.
Psions get a bad rap because their focus generation is slower than you can get from the other options, but it's automatic, and in turn based mode it has the extra benefit that you get your focus gen for the round up-front rather than trickling in per second. They also pair well with casters, particular casters that hang back from the fight (because they lose their focus gen for a round if they get hit). Psions in turn-based get 6 focus per round, and an additional 6 per round at every odd PL. So at max level, a MC psion will get 24 focus each round. Which means that as long as they aren't getting hit, they can spam PL 1 or 2 powers indefinitely, which is something other ciphers can't do (except for Ascended Ascendants receiving SoT cheese). If they are instead spending rounds casting spells from their other class, they can bank up a bunch of focus for dropping bigger spells. A minor note, if you are abusing SoT for endless buffs, you are also in the position of abusing Barring Death's Door, and casting BDD on your psion, extending it with SoT, and leaving him at 1 hit point without healing, will mean that he technically doesn't take damage even if somebody hits him, and so he will not lose his focus generation. All that said, a Beguiler is probably better than a Psion in most situations.
I personally don't think Soulblades or vanilla ciphers offer any real advantage compared to these three options. Dumping focus on melee strikes just isn't that great.
TL;DR: go Ascendant/Trickster, you'll probably be pretty happy with it. Once you play through and see how things work, you'll be able to judge for yourself what you'd like to try.