The first question that comes to my mind while picking 20 of Lataji’s best is: Should I simply enlist my favourite 20 songs, or should

I examine whether my favourites would also qualify as the “best”?Let me explain my predicament to you. Consider the following sentiments:
(1) I regard SD Burman, C Ramchandra, Madan Mohan, Khaiyyaam and Jaidev as the “best” composers ever, so should I pick 3-4 songs each of these composers, maybe pick one each from Salil Chowdhury, RD Burman, Roshan and Naushad to get my list of 20?.
(2) Two of the most intense emotions that I know of are romance and melancholy, so should I consider picking 10 songs each pertaining to these two emotions only?
(3) I regard Shailendra, Rajender Krishan, Majrooh, Sahir and Javed Akhtar as the “best” lyricists ever, therefore should I enlist only their songs? 
(4) I regard Waheeda Rehman, Madhubala, Nargis and Nutan as the “best” heroines ever, shouldn’t my picks then be from their songs only?
(5) As an album, I find songs of Anarkali, Madhumati,Abhimaan, Guide, Anpadh, Kabhi Kabhie and Woh Kaun Thi the most wholesome, should I not pick 3-4 songs each from these movies?

Clearly, there is a fallacy in each of the above lines of argument, for if I opt for any of the above criteria, or a combination thereof, I would merely be passing off my favourites as the best, and that would not be reflective of the vast oeuvre of a legendary singer.
Now the real question: What criteria do I choose to identify the 20 best songs?
With a lot of thought, I have opted for the following criteria:
a)      No two songs should be from the same composer
b)      No two songs should be from  the same lyricist
c)      No two songs should be from the same movie
d)      No two songs should be picturized on the same heroine.
e)      The identified songs should include cover all basic moods and genres such as ghazal, sad song, romantic song, prayer song, philosophical song, even a cabaret!
f)        Only popular songs would be considered
Thus, my final 20 would be from 20 different composers, penned by 20 different lyricists for 20 different movies and picturized on 20 different heroines! 
Now then, I come to my selections, given in random order:
1. Aaega Aanewala
Film: Mahal, Composer: Khemchand Prakash, Lyricist: J Nakshab, Heroine: Madhubala 
 The first cult song of hindi film industry! And how the song has stood the test of time…
2. Ae maalik tere bande hum
Film: Do Aankhein Baarah Haath, Composer: Vasant Desai, Lyricist: Bharat Vyas, Heroine: Sandhya 
 The most potent prayer song till date! Try singing it with emotion and the prayer still works… at least works for me!
3. Mohabbat aisi dhadkan hai, jo samjhayee nahin jaati
Film: Anarkali, Composer: C Ramchandra, Lyricist: Hasrat Jaipuri, Heroine: Bina Rai
You have to immerse yourself in love to know what it means…Chale aao chale aao, takaaza hai nigaahon ka, kisi ki aarzoo aise to thukrai nahin jaati..
  4. Aap ki nazron ne samjha
     Film: Anpadh, Composer: Madan Mohan, Lyricist: Raja Mehdi Ali Khan, Heroine: Mala Sinha 
 This is my all-time favourite filmi ghazal. The novelty is evident in all three leagues-lyrics, composition and crooning.
5.      Rangeela re
 Film:Rangeela Composer: S.D. Burman, Lyricist: Niraj, Heroine: Waheeda Rehman
Great composition, great rendition, and great poetry from Dev Anand’s directorial debut in 1970. Sample this:
                  Dukh mera dulha hai, birha hai doli; Aansu ki saari hai, aahon ki choli
                  Aag main piyoon re, jaise ho paani;  Naari diwaani hoon, peeda ki rani
6.  Dheere dheere machal ae dil-e-beqaraar
   Film: Anupama, Composer: Hemant Kumar, Lyricist: Kaifi Azmi, Heroine: Leela Naidu
  The cadence of the song grows on you instantly! I have been humming this one since my childhood days.
7. Aurat ne janam diya mardon ko
Film: Sadhna, Composer: N Dutta, Lyricist: Sahir Ludhianvi, Heroine: Vyjantimala
The song has a distinctly Sahir feel to it, which has been commendably composed by N Dutta and rendered by Lata in manner that instantly evokes empathy towards the manner in which the society has treated women…jab jee chaha masla kuchla, jab jee chaha dutkaar diya.
8. Ae mere dil-e-nadaan, tu gham se na ghabrana
   Film: Tower House  Composer: Ravi  Lyricist: Asad Bhopali , Heroine: Shakeela
I have always seen this song as a very potent anti-depressent, especially its second line which says Ik din to samakh legi, duniya tera afsaana
9. Ajeeb dastaan hai yeh
Film: Dil apna aur preet parayee  Composer: Shankar Jaikishan  Lyricist: Shailendra, Heroine: Meena Kumari 
  Bid the beloved all the best in life, so what if he is parting ways…mubaarkein tumhe ke tum, kisi ke noor ho gaye, kisi ke itne paas ho, ke sabse door ho gaye
10. Rahein na rahein hum
Film: Mamta, Composer: Roshan, Lyricist: Majrooh, Heroine: Suchitra Sen 
 Whether we are around or not, our ageless love would survive..even in the other world!
      Jab hum na honge, tab hamaari khaak par tum rukoge chalte chalte
      Ashkon se bheegi, chandni mein ik sadaa si sunoge chalte chalte
      Wahin par kahin, wahin par kahin hum tumse mileinge   
      Ban ke kali, ban ke saba, baagh-e-wafa mein!
11. Dikhai diye yoon
Film: Bazaar, Composer: Khaiyyaam, Lyricist: Mir Taqi Mir, Heroine: Supriya Pathak Penned by one of the doyens of urdu poetry Mir Taqi Mir, this number is beautifully composed by Khaiyyaam saa’b (the only surviving composer of the golden era!) and sung so perfectly by the nightingale!
Balance 9 songs are mentioned in the Comments section due to space constraint.