best Marantz tuners?

10b is the top, model twenty is next up, still has the scope and is more affordable.

One thing to keep in mind is that each model has some potential - but depending on it's age and how well it has been maintained (in terms of components and alignment) you might or might not hear that potential; I'm pretty sure a Marantz 150 operating at spec would sound very good; I've listened to a Marantz 10B, Yamaha CT-7000, Sony 5130, Yamaha T-2, and the Marantz 150 is a fine tuner if it has been maintained properly.

The Marantz 10b, its a living legend and solid tuner.

I'll second and re-emphasize Hi_hifi's comment about condition being a very major variable.

Also, if you are not already, be aware that a 10B in excellent condition will probably cost about as much as the retail prices of your amp and speakers combined. It is also an extremely complex design (the number of small components under its chassis is jaw-dropping), and its performance is likely to not be at or near its best if it has not been worked over in the last decade or two, by someone with the right expertise.

Another important consideration is the signal strength of the stations you will listen to, that you can receive at your location and with your antenna. If the stations you will be listening to are strong, and if you have not encountered significant issues with multipath distortion, I suspect that most of the choices that have been mentioned, and many others, will do well for you.

Before making a decision, I would suggest that in addition to the solid state units that have been mentioned you also consider the 1960's tube tuners that were made by Scott and Fisher, or the McIntosh's if you want to spend somewhat more. You'll find a pretty wide variety of "looks" to choose among, and if signal strength is good, and their condition is good, many of them will provide sound quality that approaches the 10B level.

Regards,
-- Al