Which pedal you should get depending on the sound you long for.
The ARDX20 fits perfect into the sound of the guitar and is pretty suitable for slapback or – for example- to thicken the lead tone.
But to create rhythmical delays in the style of U2 you should choose another one. It cuts the treble, partly also the bass and therefore it will always sound like a part of the guitar-signal.
The ARDX20 is based on an Ibanez AD9 of the 80s and sounds like a vintage delay.
It sounds particularly good when your guitar-sound is lightly overdriven.
By adding the Amazeo by AnalogMan (which unfortunately only is available in used condition) you also get the possibility to complete the signal by tap tempo and modulation.
There are rumors that next year AnalogMan will put a new analog-delay on the market that unites the ARDX20 with the Amazeo in a small enclosure. Perhaps it is worthwhile to wait.
Memory Lane 2
The Memory Lane 2 is much more flexible because of its tone pot. Of course it also can be adjusted quite subtle but if you-for example- put the tone pot to 2 o’clock position you will be able to create delays that become more prominent.
The in-built tap tempo and the modulation work quite well and sound pretty nice.
The maybe only disadvantage of the Memory Lane 2 is its size.
Unfortunately the Memory Lane 2 is not produced anymore and the smaller Memory Lane Jr. is a digital delay.
All in all the Memory Lane has got a more percussive attack which, for a clean sound, I prefer to the ARDX20. If I had to decide between both I would choose the Memory Lane 2 for a clean sound and the ARDX20 for an overdriven sound.
And of course it depends on the guitar and the amplifier you are using. Maybe the Memory Lane 2 will accentuate the low end a little too much.