I'd go for somple of old fashioned steam driven dials as 99.9% of aircraft out there have them. If you are lucky enough to end up flying glass then a short conversion is a snap, but if you only know glass you'll feel a bit silly when a pal says... 'do you want to fly my aeroplane'.
Also, the exams and all PPL books and courses are based on round dials, not computer screens.