I believe the v5 is a Nooelec and is comparable to the RTL v3. The RTL v4 is the latest chip. They both have different strengths and weaknesses tho.

https://www.onesdr.com/rtl-sdr-vs-nesdr-which-one-should-i-b...

A lot of the Nesdr kits come with a Ham It Up 1.3 already, which seems to be the only real difference listed besides the accuracy of the crystal oscillator being much more accurate in the Smart v5.

I'm looking at a bladeRF...