I carry a patch kit (Rema Tip Top, accept no substitute) and a spare tube plus the other stuff needed to fix a flat:
15mm wrench (on bikes with nutted axles)
Tire levers
Small pump
I've never tried tubulars... clinchers seem to be a fairly user friendly technology and are the "devil known" for me, meaning that I'm familiar with their failure modes after 50 years of riding. AFAIK tubulars are limited to narrower tires, but I could be wrong about that.