Which satellite finder is best ?

There are many inexpensive satellite meters available (search ebay) that simply measure total signal power from the satellite, as seen in the L band cable from the LNB. These meters respond to virtually all satellites and will enable you to accurately peak up the pointing. They do not help with polarisation adjustment or identifying which satellite is which and are not suitable for satellites that have only a few weak signals.

Significantly more expensive meters that identify satellites need to be pre-programmed with some details unique to the satellite, such as a particular carrier and its frequency. These meters can be very useful for installers who repeatedly need to find the same satellite. There is some initial learning to do in setting up the meter. If only used infrequently there will some doubt about whether or not the carrier programming is up to date. Remember that the meter, like a satellite TV receiver, tunes across L band 950-2050 MHz and assumes some LNB local oscillator frequency and the spectrum inverted or otherwise. If you intend to use such a meter I suggest that you test first, at your base, before you visit the customer site using the same type LNB as to be used on site.

Read more about BIRDOG meters here: https://www.satcomnow.com/satcom/pdf/BirDog_Ultra_manual.pdf

Expensive spectrum analysers are general purpose tools that will help you peak up in polarisation as well as azimuth/elevation. They are helpful for resolving interference problems as well.  A spectrum analyser will not identify the satellite unless you know the spectrum of your wanted satellite. It is helpful to have printed out copies to compare and exact information about the wanted carrier frequency, polarisation and bandwidth.

Good quality spectrum analysers, coupled with LNAs or high stability PLL LNBs, have narrow resolution bandwidth filters and are excellent for detecting and measuring very weak, narrow, signals such as low bit rate carriers and CW beacons.

Don't forget that the customer receiver (e.g. iDirect ) can be an adequate signal detection system and provided you can position its display near the antenna it will be adequate without needing any other satellite meter.