Swore I wouldn't post again but this subject is near and dear to me.
It all depends on what you are trying to achieve and what your budget is. For me, like all of my hobbies and interests, I go too far down the rabbit hole because I'm kind of a perfectionist. I always recommend books by Scott Rao
https://www.amazon.com/s?k=scott+ra...x=scott+rao,aps,173&ref=nb_sb_ss_ts-doa-p_3_9 for those who want to learn more about coffee and espresso. I have this book
https://www.amazon.com/Professional...d=1731722926&sprefix=scott+rao,aps,173&sr=8-3 from
Sweet Marie's Coffee in Oakland years ago and highly recommend it.
Making a good espresso is both an art and a science and a lot of trial and error because there are so many variables. The standard espresso machines for years have been the E61 group head designs with a boiler or two boilers but now they some better technology, however you're going to pay for it. My Vibiemme Dumobar Double version 3.5 died a few years ago after 8 years of heavy use so I've been searching for the perfect machine now for a couple of years. I don't even know if they still make Vibemme or not but I bought it from 1st Line and it cost $3,200 back in 2014. I calculated it paid for itself in about 18 months.
Seattle Coffee Gear is a great place to look because they haver some great review videos and they have espresso machines at all price points. The top of my wishlist right now is the Sanremo You and I think that's what I'm going to be getting if I just say screw it, and buy what I want.
If you are a techie and love science, I would look at the Decent Espresso Machine. They have a huge online community and open source for espresso programs that you can install.
It's kind of hard to know where to start when someone asks me what I think the best machine for them is because there are so many things you need to take into consideration. Pressure profiling is the new thing now in espresso. It was flow profiling but it's more difficult to fine tune your machine for a particular type of bean and roast. The Decent lets you control EVERY parameter! I have friends that love the Decent but these days I just want to press a button, maybe adjust a few parameters, and drink my espresso in the morning.
If you're going to drop some cash on a nice machine you also need to drop some cash on a good grinder. That Black and Decker coffee grinder you got for a wedding gift is not going to cut it (pun intended).
What someone said about oily beans is true. That usually means they are old or not stored properly or both. A good roaster will put the date the beans were roasted on their bag instead of just a use by date. I used to be a faithful Stump Town Coffee fan before Pete's bought them out, but maybe Pete's left them alone and the quality and choices are till good.
Hope this was helpful. If you have a specific question I might be able to give you my input or point you in the right direction. Good luck!