This is pretty subjective, as tastes and applications differ...
If you're looking at a dual boost/drive, such as the MXR 402, then I'd also take a look at the Full-Drive 3 by Fulltone (version 2 does not have an independent boost). I think it sounds much better (subjective), is more versatile (not subjective), and it's about the same price. Here's a good demo of it:
https://www.youtube.com/watch?v=w8w-CLxfACUProbably the best boost or drive pedal I own is the AC Booster by Xotic. It stays on nearly 100% of the time, regardless of the application, and stacks great with other drive pedals. Had the choice to do over, I would have gotten the AC Plus, but at the time the compression options and pedal size was a turn off. The Plus is a dual stage pedal with loads of options, and you can even change the signal path from pedal A to B or B to A. I'll be getting that or their BB Plus in the near future. Xotic pedals are on the pricey side, though, but they are great.
If you're set on the setups you've mentioned, then you'll just have to go to a shop and try out the MXR. A Tube Screamer is a Tube Screamer, so that's that and a clean TC boost is just that and both are true bypass, so you can't go wrong with that setup (though I've heard that the Spark boost colors sound a bit whereas an RC Booster, for example, is completely transparent). Between the MXR and Screamer+boost, I'd personally go the Screamer route.
Of course you could just keep the 250 as drive and add only the Spark, but you'll be limited if you want to push it (overdrive) harder with another pedal. Just depends on your application. All considered, I don't think you can beat the Fulltone for the price, but you should try it in person because YouTube compression colors tone.