This depends on which reactive armor variant of the M60A1 you wish to do. You have two basic choices, the USMC M60A1 RISE/Passive w/ERA or the Israeli Defense Force (IDF) M60A1 Blazer reactive armor. Although they look similar, the armor blocks are distinctly different.
The best M60A1 kit is the original Esci M60 series kit. They packaged this kit in three variants, the IDF M60 Blazer, US M60A1 and US M60A3. All the same basic kit, but only the first one comes with reactive armor. AMT/Ertl also boxed these kits for sale in the US. All three kits are currently available as reissues. The M60 Blazer and M60A1 in Italeri boxes and the M60A3 in a Revell of Germany box. This kit is not available with the USMC reactive armor. All of these kits include link & length T-142 tracks (football shaped track pads) and "finned" aluminum road wheels. The ERA parts are kind of soft as well as the IDF machine gun parts.
Tamiya makes the USMC M60A1 w/ERA. It is done up in Desert Storm markings and includes latter style steel road wheels and vinyl T-142 tracks. Decent kit, but the base M60 is not as good as the Esci/AMT/Ertl/Italeri/RoG kit.
Academy makes both the IDF and USMC variants of the M60A1 w/ERA. Its base M60 kit is an improved copy of the Tamiya M60 kit. Their USMC variant comes with and without the M9 tank dozer blade. Their IDF variant comes with and without the KMT-4 mine roller.
Gunze Sanyo made an extremely expensive USMC variant that is OOP and based on the Academy kit. Verlinden made a resin set of IDF ERA that is fairly expensive as well. Trumpeter makes a poor copy of the M60A1/A3 and it is to be avoided at all costs. It shows up in a Wasan box as well.
Here is a rundown of the various reactive armor M60A1s:
Tamiya USMC M60A1 RISE/Passive w/ERA #35157*
Esci IDF M60A1 Blazer #5042*
AMT/Ertl IDF M60A1 Blazer #8864 (same kit as above)*
Italeri IDF M60A1 Blazer #6391 (same kit as above)
Academy USMC M60A1 RISE/Passive w/ERA #1349
Academy IDF M60A1 Blazer #1358
Academy IDF M60A1 Blazer w/KMT-4 mine roller #1367
Academy USMC M60A1 RISE/Passive w/ERA w/M-9 Dozer Blade #1390*
Trumpeter(Wasan) USMC M60A1w/ERA #00309 (avoid)
Trumpeter(Wasan) IDF M60A1 W/RKM mine roller #00310 (avoid)
Verlinden IDF M60 Blazer Armor #398*
My 2003 Squadron catalog shows what is advertised as the Italeri M60A3 but pictures a USMC M60A1 w/ERA, #6397. I assume it is the Esci kit but do not know anything about the ERA pictured. I have not seen this kit on a store shelf yet.
An asterisk (*) next to a kit number indicates that I have that kit. I have many of the Esci/AMT IDF Blazer kits (about 5+) so if you have any M60 kit I can send you a set of Blazer armor for the price of postage. I have at least one of each manufacturer's M60 tank, although it may or may not be one with reactive armor.
Edit: Forgot to add that the Gunze Sanyo M60A1 w/ERA was kit #0715 and ran $125.