Which handheld network tester?

I’m trying to decide which cable tester to buy. I have 20 buildings & trailers connected by MM fiber 1995 install. 1 with coax, 2 cat 3, rest cat mixed 3 & 5. All with hubs, 3Com, HP, or ChipCom, with 5006 ChipCom concentrator in center of fiber with 3 cards or backplanes. Longest distance for fiber is 1/4 mile walking??? Copper distance??? I have Observer software & probe to move around buildings. We are supposed to rewire to 100 switched within next year.
Which tester will fit now & future?