The Daytons are fine for most, we don't know what you are re-caping. Being as my speakers had served me well for 35+ years, I went over what I wanted to spend and got Axion and Solen PP caps at parts connextion.com on sale. I was totally shocked on the improved performance across the band.
Depends on how big you're bank is. It also depends on the location of the caps in the circuit. I tend to spend considerably less on woofer shunt caps than I do caps that are in the signal path of the midrange and tweeter (especially). It also depends on how much space you have. Film caps can start to get huge as you move up in value.
For non-polar electrolytic shunt capacitors, I like the Mundorf ECap Plain capacitors. They are bigger and cost a little more than generic NPEs, but less expensive and smaller than film caps of comparable values. For smaller value woofer shunt caps (up to about 22uF) I tend to go with Axon True Caps instead of NPEs.
If that 15uF is a series midrange cap, and you have the space, I'd definitely recommend a decent film cap over an NPE. Tweeter caps, I always get the best film cap my budget will allow. May favorites so far, in terms of bang for the buck are the Clarity Cap PX series and the Sonicap Gen1. I have used both brands multiple times in the midrange and tweeter circuits of several speakers I have recapped (JBL L36 Decades, L19A and 4310B, KLH Model 23, Rectilinear III Highboys, etc.) and have been pleased with the way they sound. I usually bypass the tweeter caps with the little Vishay-Roederstein MKP1837s, but recently tries bypassing a Sonicap Gen1 with a Cornell-Dubillier 940C and like the way that combination sounds.
Replacing resistors will have less impact than replacing caps (in general), but while i have things apart, I tend to replace any old cement resistors with new Mills non-inductive wirewound resistors.
Here's a recent example of a a crossover I rebuilt using these parts (original on the left, rebuilt on the right):
Those are the crossovers for a pair of JBL L19As (2-ways with an 8" woofer). I replaced the 5 ohm 10W cement resistor with a 5 ohm 12W Mills resistor, replaced the 18uF NPE woofer shunt cap with an 18uF Axon True Cap and replaced the original mylar in wax 7uF tweeter cap with a 7uF Sonicap Gen1 bypassed with a 0.01uF Cornell-Dubilier 940C. I also moved one of the inductors and rotated it by 90 degrees to minimize coupling and shortened all the leads to clean things up an bit. I also replaced the crappy original speaker wire terminals with a pair of Dayton Audio BPA-38G heavy duty binding posts. I'm very pleased with the way they turned out and happy with the choices I made.
So, let us know a little more about this crossover you are rebuilding and how much you have in your parts budget.
