Hands down the PlutoSDR (a.k.a ADALM-PLUTO) has the best price/performance & support I've seen (and I've owned a BladeRF, LimeSDR and various RTL dongles as well).
The core radio chip itself (the AD9363) appears to be identical and/or a binned version of the AD9364 chip used in things like USRP Radios (i.e. the high-end standard bearer brand for SDR) and can be configurated to behave like it [1]. The unit price for the AD9364 chip (in low volumes) is around $200. The ENTIRE PlutoSDR is $150 and that includes a Zynq-7010 FPGA (which itself is not cheap)!
Because it's built by Analog Devices, it's generally well supported. It's designed as an educational tool so there are a lot of tutorials for beginners like PySDR. I really like the interfacing libraries (pyadi) that allow me to easily configure the SDR from a python notebook and pull an RX buffer into numpy and process away.
Your link says only early builds had the AD9364, and production builds have the AD9363. Too bad, its certainly less useful with no ability for VHF. You aren't going to get much range out of UHF with a 5mW output limit.
I've only used the RTL-SDR ones, so I can't offer any first-hand comparison. But for receive-only operations, the RTL-SDR dongles are cheap, readily available, compatible with many or most SDR related software packages, and basically "just work". YMMV, but one of those is probably where I'd suggest starting.
I've heard good things about the HackRF devices as well. The nice thing about those is that they're programmable transmitters as well, not just receivers. But they're a bit pricier as well, which is the downside. If I buy another SDR anytime soon, that will probably be the direction I go.
If you just want to _look_ at signals, a RTL-SDR kit with a basic dipole antenna (rabbit ears) and the USB dongle is like $35USD and readily available.
I would 100% recommend starting there. If you actually find yourself using it and/or enjoying it, then look at spending some more money.
If you do enjoy playing with SDR stuff, could also recommend getting an amateur radio license. Basic license is ridiculously easy to get and gives you access to legally transmit on a whole bunch of different frequency ranges and put you in contact with some other RF geeks.
You can sometimes find a good deal on a HackRF as well. It has a freq range of 1mhz to 6ghz (rx/tx). The popular RTL-SDR only has 0.5mhz to 1.7ghz freq range (rx), but costs only about 1/4.
If you're okay with (1) not supporting the guy that designed it in the first place and (2) taking a risk on a Chinese knock-off (reviews generally seem good), you can often find the Hackrf One on the usual suspect sites straight from China relatively cheaply.
There's a listing right now for just the hackrf one board at $125USD (versus a legit one at $350USD).
Hate to say it but I ordered one from there (with a metal case, high stability clock, assortment of antennas and other useful stuff) for $160.
I've had my eye on one for years, but it's just never going to be something I'm willing to drop $350+ on as part of the hobby.
I don't think you can really call them a knockoff. As far as I know, the HackRF has been designed as an opensource hardware[0], so I'd guess the designer intended it to be built by different entities.
The SDR you actually own is the best one - the cheap Chinese ones are rubbish, don't get me wrong, but you can still do a hell of a lot with a little RTL-SDR
Analog Devices have some good offerings well up the price scale but I forgot if they start at DC
