Ikr you can get from E400mmc to alx400 on that 60 and considering after the 2 to maxim Park was cancelled its now the longest first route it defo needs new refurbished busesThey should probably brand a mixture of E300s and E400s for the 6. The 5 could be doing with branding.
As for the 60/60A I think refurbed B9TLs similar to those on the 61 would be good. The 60 has too mixed a fleet. It can get anything from brand spanking new to old tat. The B9TLs are getting on a bit however the oldest are about 13 this year. They look good refurbed but it won’t be too far away before they need a replacement on the 61. I always thought the 61 was busy and deserved new buses.