Sylvania Xtravision (pink package), Narva Rangepower, Philips High Visibility, GE High Output. None of these will make an enormous improvement, it'll be an incremental improvement, BUT the improvement will be genuine, unlike the blue bulbs' pretend-improvement.
You can improve things further by installing good wiring and relays. The factory wiring is too thin; it tends to starve the bulbs.
DS